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zhannawk [14.2K]
4 years ago
15

Which statement correctly describes an atom of the element helium? (9)

Chemistry
1 answer:
Luden [163]4 years ago
8 0

C. An atom of helium has its valence electrons in its first energy level, it wouldn't and can't satisfy the Octet rule as it only has 2 electrons, but with 2, it has a full shell, as the first energy level can hold only 2 electrons.

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Answer:

  1. According to the law <br> Mass of reactants = mass of product, here <br> `underset(10 g)(CaCO_(3))rarr underset(4.4 g)(CO_(2))+underset(x)(CaO)` <br> Hence, x = 10 g - 4.4 g = 5.6 g <br> Which is mass of CaO.d
  2. In the first compound <br> Hydrogen = 5.93 % <br> Oxygen = `(100-5.93)% = 94.07 %` <br> In the second compound <br> Hydrogen = 11.2 % <br> Oxygen `= (100-11.2)%=88.8%` <br> In the first compound the number of parts by mass of oxygen that combine with one part by mass of hydrogen `=(94.07)/(5.93)=15.86` parts ...
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  4. Refer to the above attachment

Explanation:

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5 0
2 years ago
A scientist is comparing two cells. One cell, cell A, is from a unicellular organism, and the other cell, cell B, is from a mult
marishachu [46]
Cells are considered the basic units of life in part because they come in discrete and easily recognizable packages. That's because all cells are surrounded by a structure called the cell membrane — which, much like the walls of a house, serves as a clear boundary between the cell's internal and external environments. The cell membrane is sometimes also referred to as the plasma membrane.

Cell membranes are based on a framework of fat-based molecules called phospholipids, which physically prevent water-loving, or hydrophilic, substances from entering or escaping the cell. These membranes are also studded with proteins that serve various functions. Some of these proteins act as gatekeepers, determining what substances can and cannot cross the membrane. Others function as markers, identifying the cell as part of the same organism or as foreign. Still others work like fasteners, binding cells together so they can function as a unit. Yet other membrane proteins serve as communicators, sending and receiving signals from neighboring cells and the environment — whether friendly or alarming

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7 0
3 years ago
Read 2 more answers
Substances that are created and come out of a chemical reaction
Nutka1998 [239]
May be reactants.....

5 0
3 years ago
What happens inside an air-filled balloon is squeezed on all sides?
Blizzard [7]

Answer: The air molecules move closer together.

Explanation:

6 0
3 years ago
[please answer fast!] If the hydroxide ion concentration is 2x10^-3 M, what is the pH of the solution? Show your working.
Verizon [17]

Answer:

pH = 11.30

Explanation:

pH is defined as -log [H⁺]

To find [H⁺] from [OH⁻] -Concentration of hydroxide ion-, we must use the equilibrium of water:

H₂O(l) ⇄ H⁺(aq) + OH⁻(aq)

Keq = 1x10⁻¹⁴ = [H⁺] [OH⁻]

[H⁺] = 1x10⁻¹⁴ / [OH⁻]

[H⁺] = 1x10⁻¹⁴ / 2x10⁻³M

[H⁺] = 5x10⁻¹²M

pH = -log (5x10⁻¹²M)

<h3>pH = 11.30</h3>

6 0
3 years ago
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